Chen Weijie

The development of the first high‐performance, printable CsPbI₃ solar cells via an ambient blade‐coating technique is reported. High‐quality CsPbI₃ films are grown via the introduction of a low concentration of the multifunctional molecular additive Zn(C₆F₅)₂. As a result, the additive‐treated perovskite solar cell delivers a power conversion efficiency (PCE) of 19%.

Abstract

All‐inorganic CsPbI₃ holds promise for efficient tandem solar cells, but reported fabrication techniques are not transferrable to scalable manufacturing methods. Herein, printable CsPbI₃ solar cells are reported, in which the charge transporting layers and photoactive layer are deposited by fast blade‐coating at a low temperature (≤100 °C) in ambient conditions. High‐quality CsPbI₃ films are grown via introducing a low concentration of the multifunctional molecular additive Zn(C₆F₅)₂, which reconciles the conflict between air‐flow‐assisted fast drying and low‐quality film including energy misalignment and trap formation. Material analysis reveals a preferential accumulation of the additive close to the perovskite/SnO₂ interface and strong chemisorption on the perovskite surface, which leads to the formation of energy gradients and suppressed trap formation within the perovskite film, as well as a 150 meV improvement of the energetic alignment at the perovskite/SnO₂ interface. The combined benefits translate into significant enhancement of the power conversion efficiency to 19% for printable solar cells. The devices without encapsulation degrade only by ≈2% after 700 h in air conditions.

Graphene‐based materials have demonstrated tremendous potentials in boosting the efficiency and stability of planar perovskite solar cells (PSCs). A comprehensive overview that focused on the specific applications of graphene in planar PSCs has never been published before. Herein the recent applications of graphene in planar PSCs are systematically discussed and concluding perspectives on current challenges and future developments are proposed.

Metal halide perovskite solar cells (PSCs) have recently become the most promising new‐generation solar cells, with a breathtaking growth of efficiency from 3.8% to 25.2% in just one decade. Scientists have abandoned the traditional high‐temperature‐processed mesoscopic layer of the initial mesoscopic PSCs in designing and manufacturing planar PSCs. This new feature endows planar PSCs with possibilities of low‐temperature processibility and large‐scale production. Nevertheless, the advancement of planar PSCs remains limited by two bottlenecks: charge loss and device degradation. To address these two issues, researchers have adopted graphene‐based materials, which demonstrate tremendous potentials due to their superb optical transparency, outstanding carrier mobility, remarkable electrical conductivity, and superior physicochemical stability. Defects inside films and at interfaces are regulated by graphene, thereby contributing to more efficient charge extraction and suppressed charge recombination. The graphene protective layer enhances the moisture and heat stability of planar PSCs, thereby extending the lifetime of devices. Herein, the typical synthesis methods of graphene and the recent applications of graphene in planar PSCs are summarized and discussed. Furthermore, concluding perspectives on current challenges and the future development of graphene in planar PSCs are proposed.

Herein, a bulk heterojunction structure hybridizing SnS QDs and CsPbBr₃ is designed as an absorber layer for solar cells. The prominent SnS QD–CsPbBr₃ structure improves the crystallinity of perovskite, enhances the charge transfer efficiency, and reduces the trap state density of the CsPbBr₃ film, thereby further boosting the photoelectric performance of perovskite solar cells.

Inorganic cesium lead halide perovskite solar cells (PSCs) have attracted great attention due to their remarkable thermal and moisture stability. However, the low photoelectric conversion efficiency (PCE) of inorganic PSCs due to the high trap state density, high carrier recombination rate, and poor carrier transport kinetics impedes their industrial applications. Herein, a remarkable bulk heterojunction structure coupling SnS quantum dots (QDs) with CsPbBr₃ is prepared for the first time via a facile spin‐coating process using a SnS‐QD‐dispersed toluene solution as an antisolvent. The introduction of SnS QDs provides extra crystallization sites and promotes the crystallization of perovskites along (100) and (200) faces. Meanwhile, the bulk heterojunction structure with matched energy structure can effectively reduce the trap state density of the perovskite film and improves the dynamic performance of carriers, suppressing the charge recombination rate and effectively boosting the PCE of solar cells. As a result, the optimal bulk heterojunction solar cell achieves a PCE of 8.01%, about 52% higher than that of the pristine solar cell. This work provides a low‐cost and facile strategy for preparing high‐performance bulk heterojunction PSCs and an effective method to boost the PCE by nontoxic QDs.

High‐performance thick‐film OSCs are essential for well matching the roll‐to‐roll (R2R) technology to realize its large‐area potential application. The critical factors and smart strategies on performance improvement of thick‐film OSCs are well summarized to inspire more fantastic ideas on achieving efficient thick‐film OSCs. Meanwhile, the challenges on achieving efficient thick‐film OSCs are outlined.

To date, the power conversion efficiency (PCE) of lab‐scale organic solar cells (OSCs) has exceeded 17%, which heralds the bright future for commercial applications of OSCs. High‐performance OSCs with thick active layers are essential for large‐scale production. First, the relatively thick active layers should be more compatible with the roll‐to‐roll (R2R) large‐area processing, which is conducive to forming uniform and defect‐free active layers in the process of high‐speed, mass production. Second, the thick active layers can absorb more incident light in their spectral range, which helps thick‐film OSCs to obtain relatively high short‐circuit current density (J _SC). So far, relatively little attention has been paid to thick‐film OSCs, and the PCE of thick‐film OSCs lags far behind its thin‐film analogues. Herein, the recent development of thick‐film OSCs is highlighted and the critical limit factors on the PCE of thick‐film OSCs are pointed out. Some strategies are highlighted to improve the efficiency of thick‐film OSCs. This review study will be helpful to the researchers engaging in the development of efficient thick‐film OSCs.

Herein, the study and integration of a novel nanostructure based on Au nanoparticles (NPs) aggregates on the back contact of an ultrathin Cu(In,Ga)Se₂ solar cell are developed. The NPs are effectively encapsulated with a dielectric matrix, providing a broadband external quantum efficiency enhancement that translates to a 17.4% improvement of the short‐circuit current density over a reference device.

The incorporation of nanostructures in optoelectronic devices for enhancing their optical performance is widely studied. However, several problems related to the processing complexity and the low performance of the nanostructures have hindered such actions in real‐life devices. Herein, a novel way of introducing gold nanoparticles in a solar cell structure is proposed in which the nanostructures are encapsulated with a dielectric layer, shielding them from high temperatures and harsh growth processing conditions of the remaining device. Through optical simulations, an enhancement of the effective optical path length of approximately four times the nominal thickness of the absorber layer is verified with the new architecture. Furthermore, the proposed concept in a Cu(In,Ga)Se₂ solar cell device is demonstrated, where the short‐circuit current density is increased by 17.4%. The novel structure presented in this work is achieved by combining a bottom‐up chemical approach of depositing the nanostructures with a top‐down photolithographic process, which allows for an electrical contact.

An all‐evaporation technique is developed for perovskite solar modules. With a novel two‐step strategy of active‐layer design, homogeneous large‐area perovskite films are prepared via evaporation of first PbI₂ and then CH₃NH₃I. An 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ)‐doped 4,4′,4″‐tris(N‐(aphthalene‐2‐yl)‐N‐phenylamino)triphenylamine (2T‐NATA) hybrid hole‐transporting layer is deposited via coevaporation. A power conversion efficiency beyond 13% is achieved with the flexible perovskite solar module.

Large‐area homogeneous and uniform perovskite films are key to the mass production of perovskite solar cells, especially the flexible ones. Different from the solution‐processed preparation, herein an all‐evaporation technique is developed for both perovskite films and the hole‐transporting layer in the modules. With the two‐step strategy of active‐layer design, homogeneous large‐area perovskite films are prepared via evaporation of first PbI₂ and then CH₃NH₃I. An 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ)‐doped 4,4′,4″‐tris(N‐(aphthalene‐2‐yl)‐N‐phenylamino)triphenylamine (2T‐NATA) hybrid hole‐transporting layer is deposited on the indium‐tin‐oxide electrode via coevaporation. A power conversion efficiency (PCE) beyond 13% is achieved with the as‐prepared flexible perovskite solar module (active area of 16.0 cm²), which exhibits both higher stability and higher efficiency than the conventional solution‐processed module using poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) (PEDOT:PSS) as the hole‐transporting material. This novel strategy of all‐evaporation functional layers provides a feasible way for the industrialization of flexible perovskite solar cells.

The drastic open‐circuit voltage drop at low temperatures in bulk heterojunction and bilayer organic solar cells is found to be dominated by the competition between the photocurrent and the parasitic leakage current. The leakage current should thus be carefully optimized in temperature dependent analysis as well as in practical applications.

While the efficiency of organic solar cells (OSCs) has increased considerably in recent years, there remains a significant gap between the experimental open‐circuit voltage (V _OC) and the theoretical limit. Understanding the origin of this energy loss is important for the future development of OSCs, with temperature‐dependent measurement of V _OC an important approach to help unlock the underlying physics. Interestingly, previous studies have observed a reduction in V _OC at low temperature that has been attributed by different studies to different phenomena. To resolve this issue, herein the temperature dependence of V _OC of various polymer‐based OSC systems covering a range of acceptor types (fullerene, polymer, and non‐fullerene small molecule) as well as device architectures (conventional, inverted, blend and bilayer) is studied. Across all systems studied, V _OC reduction at low temperatures is associated with high parasitic leakage current, providing a universal explanation for this phenomenon in OSCs. Moreover, it is shown that leakage current, which causes complexity in the analysis and raises reliability concerns in potential applications, can be suppressed by varying device architecture, providing an effective approach for analyzing the true temperature dependence of V _OC.

A novel perovskite‐compatible carbon electrode based on low polar alkane solvent decreases the defect at CsPbI₂Br/carbon interface and hinders moisture in the atmosphere. The champion device obtains a power conversion efficiency (PCE) of 13.16% and provides outstanding stability with a PCE maintaining 93% of the initial value after 1000 h under a humidity of 30–40% without additional encapsulation.

Carbon electrodes are a promising alternative to metal electrodes in the access of high‐stable and low‐cost perovskite solar cells (PSCs). However, polar components (including cyclohexanone, terpineol, etc.) in commercial carbon pastes for carbon electrodes usually corrode perovskite materials, thereby deteriorating the photovoltaic performance of the resulting solar cells. Therefore, the development of perovskite‐compatible carbon pastes and carbon electrodes is of great significance in obtaining high‐performance carbon‐based PSCs. Herein, carbon pastes based on low polar alkane solvents are developed for perovskite‐compatible carbon electrode (PCCE) in the construction of carbon‐based CsPbI₂Br PSCs. The optimized cells based on PCCE offer a champion efficiency of 13.16% (J _SC = 14.33 mA cm⁻², V _OC = 1.22 V, and fill factor (FF) = 0.75), which is remarkably higher than that of commercial carbon paste‐derived counterparts (11.51%). Even without encapsulation, CsPbI₂Br PSCs based on PCCE maintain over 93% of their initial efficiency in an air atmosphere with a humidity of 30–40% for over 1000 h.

Introduction of multi‐cation hybrid halide perovskite quantum dots reduces ionic defects at the surface and grain boundaries via a solid‐state interdiffusion process. The enhanced moisture and photostability enable power conversion efficiency (PCE) exceeding 21% to be achieved with more than 90% of its initial PCE retained on exposure to continuous illumination of more than 550 h.

Abstract

Realization of reduced ionic (cationic and anionic) defects at the surface and grain boundaries (GBs) of perovskite films is vital to boost the power conversion efficiency of organic–inorganic halide perovskite (OIHP) solar cells. Although numerous strategies have been developed, effective passivation still remains a great challenge due to the complexity and diversity of these defects. Herein, a solid‐state interdiffusion process using multi‐cation hybrid halide perovskite quantum dots (QDs) is introduced as a strategy to heal the ionic defects at the surface and GBs. It is found that the solid‐state interdiffusion process leads to a reduction in OIHP shallow defects. In addition, Cs⁺ distribution in QDs greatly influences the effectiveness of ionic defect passivation with significant enhancement to all photovoltaic performance characteristics observed on treating the solar cells with Cs_0.05(MA_0.17FA_0.83)_0.95PbBr₃ (abbreviated as QDs‐Cs5). This enables power conversion efficiency (PCE) exceeding 21% to be achieved with more than 90% of its initial PCE retained on exposure to continuous illumination of more than 550 h.

The inclusion of a novel in situ polymerizable ionic liquid, 1,3‐bis(4‐vinylbenzyl)imidazolium chloride ([bvbim]Cl), allows perovskite films to be manufactured under humid environments, conferring improved materials quality, higher power conversion efficiency, and long‐term stability.

Abstract

Despite the excellent photovoltaic properties achieved by perovskite solar cells at the laboratory scale, hybrid perovskites decompose in the presence of air, especially at high temperatures and in humid environments. Consequently, high‐efficiency perovskites are usually prepared in dry/inert environments, which are expensive and less convenient for scale‐up purposes. Here, a new approach based on the inclusion of an in situ polymerizable ionic liquid, 1,3‐bis(4‐vinylbenzyl)imidazolium chloride ([bvbim]Cl), is presented, which allows perovskite films to be manufactured under humid environments, additionally leading to a material with improved quality and long‐term stability. The approach, which is transferrable to several perovskite formulations, allows efficiencies as high as 17% for MAPbI₃ processed in air % relative humidity (RH) ≥30 (from an initial 15%), and 19.92% for FAMAPbI₃ fabricated in %RH ≥50 (from an initial 17%), providing one of the best performances to date under similar conditions.

Arising from the lubricant role of WS₂ nanoflakes between ETL and perovskite, the tensile strain in the perovskite film is released for a uniform perovskite with low defect density and high activation energy for ion migration. This significantly improves the device performance and stability.

Abstract

Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron‐transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all‐inorganic CsPbBr₃ perovskite solar cells (PSCs) because of their higher crystallization temperatures and thermal expansion coefficients. Herein, the interfacial strain is released by fabricating a WS₂/CsPbBr₃ van der Waals heterostructure owing to their matched crystal lattice structure and the atomically smooth dangling bond‐free surface to act as a lubricant between ETL and CsPbBr₃ perovskite. Arising from the strain‐released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65 % with an ultrahigh open‐circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity (80 %) attack over 120 days.

2D perovskites are of great importance to increase both the efficiency and stability of perovskite interfaces. Motivated by the stronger halogen bond interaction, (5FBzAI)₂PbI₄ used as a capping layer in 3D/2D systems self‐organizes with an in‐plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V _oc, and remarkable operational stability.

Abstract

Despite organic/inorganic lead halide perovskite solar cells becoming one of the most promising next‐generation photovoltaic materials, instability under heat and light soaking remains unsolved. In this work, a highly hydrophobic cation, perfluorobenzylammonium iodide (5FBzAI), is designed and a 2D perovskite with reinforced intermolecular interactions is engineered, providing improved passivation at the interface that reduces charge recombination and enhances cell stability compared with benchmark 2D systems. Motivated by the strong halogen bond interaction, (5FBzAI)₂PbI₄ used as a capping layer aligns in in‐plane crystal orientation, inducing a reproducible increase of ≈60 mV in the V _oc, a twofold improvement compared with its analogous monofluorinated phenylethylammonium iodide (PEAI) recently reported. This endows the system with high power conversion efficiency of 21.65% and extended operational stability after 1100 h of continuous illumination, outlining directions for future work.

A composite consisting of 1D cation‐doped TiO₂ brookite nanorod embedded by 0D fullerene is investigated as a top modification buffer for inverted perovskite photovoltaic (IP‐PV) cells. The resultant IP‐PV displays an efficiency exceeding 22% with a favorable stability. This work opens up more opportunities in expanding the material inventory for charge transfer layer in perovskite solar cells development and application.

Abstract

Simultaneously achieving high efficiency and high durability in perovskite solar cells is a critical step toward the commercialization of this technology. Inverted perovskite photovoltaic (IP‐PV) cells incorporating robust and low levelized‐cost‐of‐energy (LCOE) buffer layers are supposed to be a promising solution to this target. However, insufficient inventory of materials for back‐electrode buffers substantially limits the development of IP‐PV. Herein, a composite consisting of 1D cation‐doped TiO₂ brookite nanorod (NR) embedded by 0D fullerene is investigated as a top modification buffer for IP‐PV. The cathode buffer is constructed by introducing fullerene to fill the interstitial space of the TiO₂ NR matrix. Meanwhile, cations of transition metal Co or Fe are doped into the TiO₂ NR to further tune the electronic property. Such a top buffer exhibits multifold advantages, including improved film uniformity, enhanced electron extraction and transfer ability, better energy level matching with perovskite, and stronger moisture resistance. Correspondingly, the resultant IP‐PV displays an efficiency exceeding 22% with a 22‐fold prolonged working lifetime. The strategy not only provides an essential addition to the material inventory for top electron buffers by introducing the 0D:1D composite concept, but also opens a new avenue to optimize perovskite PVs with desirable properties.

The application of a low frequency alternating electric field on hybrid perovskite can evidently induce irreversible change of grains/crystal domains and distribution of ionic species in the bulk, leading to tunable opto‐electronic properties and significantly increased efficiency in inverted MAPbI₃ cells without additional treatments and impressive intrinsic long‐term and thermal stability in air without encapsulation.

Abstract

With the rapid development of hybrid metal halide perovskites, controlling and understanding their growth processes have become an important but challenging task. In this paper, alternating electric field as an effective modulation method that acts on the intermediate state in perovskite formation under ambient conditions is introduced. The morphology and microstructure of the as‐formed perovskites can be effectively controlled by tuning simple physical parameters such as the frequency and amplitude, which have shown strong impact on the motion of ionic species and thus influences the formation of materials. Furthermore, the optic and electronic properties of the perovskite (such as the band position) can also be easily tuned by the field parameters. Finally, a conversion efficiency of 19.08% can be achieved in MAPbI₃ device without any doping or additional treatment, with impressive ambient and thermal stability without encapsulation. This result has not only illustrated a new physical approach for material fabrication, but also facilitates deeper understanding of the formation mechanism and generally shed light to the development of more devices and materials.

A dual‐ion‐migration phenomenon and its underlying possible mechanism are reported for the lead‐free double perovskite Cs₂AgBiBr₆, where the diffusive behavior of both Ag and Br contribute significantly to the degradation of the perovskite thin‐film and long‐term operational stability of the Cs₂AgBiBr₆ solar cells.

Abstract

Lead‐free double perovskite Cs₂AgBiBr₆ has attracted increasing research interest in addressing the toxicity and stability challenges confronted by lead halide perovskites. While most of the studies on this Cs₂AgBiBr₆ material have been focusing on photovoltaic performance and potential applications, its long‐term stability and degradation mechanism are well under‐explored. Herein, high‐quality Cs₂AgBiBr₆ thin‐films are developed for lead‐free double perovskite solar cells with a decent efficiency of 1.91%. By exploring the ambient stability of these photovoltaic devices, it is found that the Cs₂AgBiBr₆ exhibits a unique dual‐ion‐migration phenomenon, where Ag and Br ions gradually diffuse through the hole‐transporting layer in the long‐term operation. This phenomenon leads to the degradation of the Cs₂AgBiBr₆ perovskite and subsequent device failure. Theoretical calculations indicate that low formation energies of the Ag and Br vacancies, and low diffusive energy barriers contribute to the dual‐ion‐migration effect. A possible mechanism involving a vacancy‐mediated ion‐migration is proposed to explain this phenomenon. These key findings are essential for halide double perovskites not only in providing a new knowledge base for further addressing the challenge of double perovskite stability, but also in extending their optoelectronic/electronic applications where mixed electronic, ionic and photonic properties may be desired.

Solid‐state ¹⁹F magic angle spinning nuclear magnetic microscopy and elemental mapping are introduced to probe the structures of ternary and quaternary blends. The presence of the individual guest paths minimizes the influence on charge generation and transport of the host system, allowing cooperation of the parallel‐like subcells, producing impressive 17.2% efficiency via a quaternary strategy.

Abstract

Ternary strategies show over 16% efficiencies with increased current/voltage owing to complementary absorption/aligned energy level contributions. However, poor understanding of how the guest components tune the active layer structures still makes rational selection of material systems challenging. In this study, two phthalimide based ultrawide bandgap polymer donor guests are synthesized. Parallel energies between the highest occupied molecular orbitals of host and guest polymers are achieved via incorporating selnophene on the guest polymer. Solid‐state ¹⁹F magic angle spinning nuclear magnetic spectroscopy, graze‐incidence wide‐angle X‐ray diffraction, elemental transmission electron microscopy mapping, and transient absorption spectroscopy are combined to characterize the active layer structures. Formation of the individual guest phases selectively improves the structural order of donor and acceptor phase. The increased electron mobility in combination with the presence of the additional paths made by the guest not only minimizes the influence on charge generation and transport of the host system but also contributes to increasing the overall current generation. Therefore, phthalimide based polymers can be potential candidates that enable the simultaneous increase of open‐circuit voltage and short‐circuit current‐density via fine‐tuning energy levels and the formation of additional paths for enhancing current generation in parallel‐like multicomponent organic solar cells.

The relatively large non‐radiative recombination voltage loss (ΔV _non‐rad) is the main challenge for the development of organic solar cells (OSCs). ΔV _non‐rad of OSCs can be effectively reduced to 0.16 V by adopting material combinations that deliver high E _CT (the energy of charge‐transfer state) and low ΔE _CT (energetic difference between singlet excited state and CT state), together with chlorination in donors.

Abstract

Compared with inorganic or perovskite solar cells, the relatively large non‐radiative recombination voltage losses (ΔV _non‐rad) in organic solar cells (OSCs) limit the improvement of the open‐circuit voltage (V _oc). Herein, OSCs are fabricated by adopting two pairs of D–π–A polymers (PBT1‐C/PBT1‐C‐2Cl and PBDB‐T/PBDB‐T‐2Cl) as electron donors and a wide‐bandgap molecule BTA3 as the electron acceptor. In these blends, a charge‐transfer state energy (E _CT) as high as 1.70–1.76 eV is achieved, leading to small energetic differences between the singlet excited states and charge‐transfer states (ΔE _CT ≈ 0.1 eV). In addition, after introducing chlorine atoms into the π‐bridge or the side chain of benzodithiophene (BDT) unit, electroluminescence external quantum efficiencies as high as 1.9 × 10⁻³ and 1.0 × 10⁻³ are realized in OSCs based on PBTI‐C‐2Cl and PBDB‐T‐2Cl, respectively. Their corresponding ΔV _non‐rad are 0.16 and 0.17 V, which are lower than those of OSCs based on the analog polymers without a chlorine atom (0.21 and 0.24 V for PBT1‐C and PBDB‐T, respectively), resulting in high V _oc of 1.3 V. The ΔV _non‐rad of 0.16 V and V _oc of 1.3 V achieved in PBT1‐C‐2Cl:BTA3 OSCs are thought to represent the best values for solution‐processed OSCs reported in the literature so far.

The desired α‐FAPbI₃ perovskite phase is stabilized by protecting it with a two‐dimensional (2D) IBA₂FAPb₂I₇ (IBA=iso‐butylammonium) overlayer, formed via stepwise annealing. The α‐FAPbI₃/IBA₂FAPb₂I₇‐based perovskite solar cell (PSC) reached a high power conversion efficiency (PCE) of close to 23 %. It showed excellent operational stability, retaining around 85 % of its initial efficiency under severe combined heat and light stress.

Abstract

As a result of their attractive optoelectronic properties, metal halide APbI₃ perovskites employing formamidinium (FA⁺) as the A cation are the focus of research. The superior chemical and thermal stability of FA⁺ cations makes α‐FAPbI₃ more suitable for solar‐cell applications than methylammonium lead iodide (MAPbI₃). However, its spontaneous conversion into the yellow non‐perovskite phase (δ‐FAPbI₃) under ambient conditions poses a serious challenge for practical applications. Herein, we report on the stabilization of the desired α‐FAPbI₃ perovskite phase by protecting it with a two‐dimensional (2D) IBA₂FAPb₂I₇ (IBA=iso‐butylammonium overlayer, formed via stepwise annealing. The α‐FAPbI₃/IBA₂FAPb₂I₇ based perovskite solar cell (PSC) reached a high power conversion efficiency (PCE) of close to 23 %. In addition, it showed excellent operational stability, retaining around 85 % of its initial efficiency under severe combined heat and light stress, that is, simultaneous exposure with maximum power tracking to full simulated sunlight at 80 °C over 500 h.

Efficient triple‐junction tandem PSCs are achieved by optimizing the middle subcell thickness (t _M) in the presence of controlled hybrid interconnection layers between each subcell. The high FF (74.3%) and V _OC (2.14 V), leading to 13% PCE, can be realized at t _M = 60 nm due to the harmony between the physical leakage and light‐harvesting characteristics.

Making multijunctions in organic solar cells with solution‐processed polymeric bulk heterojunction (BHJ) layers, i.e., tandem polymer solar cells (PSCs), has been one of the state‐of‐the‐art approaches for the last two decades. Tandem PSCs can overcome the single‐junction Shockley–Queisser limit by improving light absorption as they can exploit the polymeric BHJ layers with poor charge carrier mobility as subcells with limited thickness. Herein, 13% efficient triple‐junction tandem PSCs with a nanocrated hybrid interconnection layer (hICL) can be achieved by controlling the BHJ thickness (60 nm) of middle subcells is demonstrated. The open‐circuit voltage and fill factor (FF) of the optimized triple‐junction tandem PSCs reach 2.14 V and 74.3%, respectively. The present approach of middle subcell thickness control, using the reproducible hICL‐based multilayer stacking technology, delivers a promising way to further extend the number of junctions leading to high efficiency tandem PSCs with enhanced open‐circuit voltages and FFs.

Herein, mesoscopic model of a photoactive layer based on mixtures of conjugated copolymers and inorganic nanoparticles is proposed and studied by means of dissipative particle dynamics simulations. The results show a possible approach to the control morphology of the photoactive layer for obtaining optimal bicontinuous charge transport paths for holes and electrons.

Mixtures of conjugated polymers (CPs) as donors and inorganic semiconducting nanoparticles (NPs) as acceptors are considered to be promising materials for photoactive layers of bulk heterojunction hybrid solar cells (HSCs). To reach the high power conversion efficiency of HSC, the morphology of the photoactive layer for providing optimal charge transport paths is designed. Herein, the coarse‐grained model for predicting the morphology of nanocomposites based on semiconducting CPs and NPs is used. For polymer matrix, well‐known CPs such as poly(3‐hexythiophene) (P3HT), poly [thieno [3,4‐b] thiophene/benzodithiophen] (PTB7), and poly [[2,6′‐4,8‐ di(5‐ethylhexylthienyl)benzo[1,2‐b;3,3‐b] dithiophene][3‐fluoro‐ 2[(2‐ethylhexyl) carbonyl] thieno[3,4‐b]thiophenediyl]] (PTB7‐Th) are selected. For NP fillers, PbS quantum dots modified by ligands (like, e.g., oleic acid) are selected. Via mesoscale computer simulations, it is shown that by choosing appropriate ligands for NPs and varying the weight fraction of NPs, the morphology with bicontinuous charge transport paths for holes and electrons is obtained. Such morphologies are observed in models of homopolymer/NP blends for the first time. This finding is in reasonable agreement with the recent experimental results on these systems.

The optimized ratio of chlorinated organic salt benzyltriethylammonium chloride ([BZTAm]Cl) is helpful for the interfacial defect passivation at the perovskite/PC₆₁BM interface. The corresponding perovskite film treatment produces high‐quality film, suppresses nonradiative recombination, and promotes the energy levels matching, which results in remarkably improved device performance and environmental stability.

In perovskite solar cells (PSCs), the interfaces between perovskite film and charge transport layers have an enormous influence on the device performance and stability. Recently, it has been proven that the surface defect passivation of perovskite layer is an effective strategy to improve the device efficiency. Herein, an organic ammonium salt benzyltriethylammonium chloride ([BZTAm]Cl) is used as an ultra‐thin modification layer in perovskite films in MAPbI₃ PSCs for passivating the surface defects. The obtained results demonstrate that the [BZTAm]Cl modifier improves the crystallization/morphology of perovskite film and effectively aligns the energy levels with the corresponding charge‐transporting layers, suppressing the nonradiative recombination and reducing the trap state density. As a result, a champion device efficiency of 20.45% is achieved for optimized concentration of [BZTAm]Cl in comparison with 17.87% for the control device. Moreover, the unencapsulated device presents a good long‐term stability after aging in an ambient environment with 40–50% relative humidity conditions for 30 days.